Method and apparatus for spinning yarns of staple fibers and filaments

ABSTRACT

In a pneumatic spinning apparatus, loose fiber ends are spread laterally from a sliver of staple fibers before the sliver is twisted with a sliver of continuous filaments into a yarn in a tube by a helical air stream. The loose fiber ends form a surface layer of the yarn which is deposited last and is therefore less tightly through than the core predominantly consisting of the continuous filaments and the remainder of the staple fibers. When the twisting air and the tightly spun yarn pass into a chamber of much greater cross section, the twisting action of the air on the yarn is relaxed, and the yarn untwists until the twist in the surface layer or shell is reversed to balance the reduced twist in the core. Backward propagation of the twist toward the intake end of the apparatus is prevented by a brake consisting of a screw whose flights bound a helical guide duct. The slivers move thorugthe duct in frictional engagement with the stem of the screw and start twisting as they approach the end of the duct near the twisting zone.

- United States Patent 11 1 SPINNING YARNS OF STAPLE FIBERS AND FILAMENTS I [76] Inventor: Konrad Gotzfried, Gabelsberger Strasse 75, Goggingen, Germany 22 Filed: on. 5, 1971 211 App]. No.: 186,655

[11] 3,722, 198 Gotzfried Mar. 27, 1973 [54] METHOD AND APPARATUS FOR Primary Examiner-John Petrakes AttorneyKur1; Kelman [57] ABSTRACT the sliver is twisted with a sliver of continuous filamerits into a yarn in a tube by a; helical air stream. The loose fiber ends form a surface layer of the yarn which [30] Forelgn Application Priority is deposited last and is therefore less tightly through Oct. 7, 1970 Germany ..P 20 49 186.5 than the core predominantly consisting of the continuous filaments and the remainder of the staple fibers. [52] US. Cl. ..57/58.89, 57/58.95, 57/156 When the twisting air and the tightly spun yarn pass [51] Int. Cl. ...D01h 1/12 into a chamber of much greater cross section, the [58] Field of Search.,..' ..57/58.89-58.95, twisting action of the air on the yarn is relaxed, and f 57/ 156 the yarn untwists until the twist in the surface layer or shell is reversed to balance the reduced twist in the [561' References Cited core. Backward propagation of the twist toward the intake end of the apparatus is prevented by a brake UNITED STATES PATENTS consisting of a screw whose flights bound a helical 2,853,847 9/1958 Keeler'etal. ..57 5s.s9 x guideducti Th slivers move thorugthe dud in flic- 2,911,783 11 1959 G otzfned ..57/58.95 nal engagementwith the stem of the screw and start 2,926,483 3/1960 Keeler et a1.) ....57/58 .95 twisting as they approach the-end of the duct near the 2,928,228 8/1960 Gotzfried ....57/58.89 twisting Zone. 3,llO,l50 11/1968 Kyame etal ....57/58l89 3,295,307 1/1967 Kyame et al ..57/58.89 10 Claims, 4 Drawing Figures I. r I'- 1. 1A I 2 20 ,7 a 90 1.0 1.

fibers jointly in pneumatic spinning equipment, but the yarns produced by knownmethods are of limitedtensile strength.

An object of. the invention is the provision of stronger yarns of the type described than havebeen available heretofore from the same constituent materials. 7

With this object and others in view, as will hereinafter become apparent, the method of the invention permits a yarn to be spun from a first elongated sliver of staple fibers and a second elongated sliver of continuous filaments in which the fibers and the filaments are sequentially passed through an intake zone, abraking zone, a twisting zone, and a relaxing zone. In the intake zone, the two slivers are moved longitu-' dinally in transversely offset relationship, thatis, without being twisted. together. Loose ends of the staple fibers are spread'laterally from the remainder of the first sliver at this stage. In the twisting zone, a helical air stream is generated about the slivers at a velocity sufficient to twist the slivers untila yarn is formed whose tightly twisted core portion is constituted predominantly by the filaments and the afore-mentioned remainder of the staple fiber sliver, whereas a less tightly twisted .shell portionis. predominantly constituted by the loose ends of the staple fibers. I

Propagation of the twist into the intake zone is prevented by braking the slivers in the braking zone. The twisting action of the helical air stream on the yarn is relaxed in the relaxing zone until the core portion'is partly untwisted, thetwist in the shell portion of the yarn is reversed, and the reversed twist in the shell por+ tion balances the remaining twist in the core portion. A yarn having balanced opposite twists in the core and shell portions thereof may then relaxing zone.-

, The-apparatus employed in carrying out this method includes several tubular sections which jointly define anelongated channelopento the atmosphere in a first section for receiving fibers to be spun. The channel 7 portion in this first section is a slot of elongated cross section. A twisting portion of the channel is'defined by a second tubular section and is of circular cross section. Aithird section defines therein a chamber portion of the channel whose cross section is much greater than that of the twisting portion.

- An, air stream is generated in the slot and has a first component longitudinal of the channel and a second component longitudinal of the cross section of the slot. A helical air stream is generated in the twisting portion be discharged from the Other features, additional objects, and many of the attendant advantages of this invention will readily be appreciated as the same becomes better understood by reference to the following detailed description of a preferred embodiment when considered in connectionwith the accompanying drawing in which:

FIG. 1 shows spinning apparatus of the invention in fragmentary elevational section;

FIG. 2 is a fragmentary, sectional plan view of the apparatus of FIG. 1;

FIG. 3 shows a portion of the apparatus of FIG. 2 on a larger sclae; and

FIG. 4 illustrates the spinning action of the apparatus of FIGS. 1 to 3 in a partly diagrammatic manner.

Referring now-to the drawing in detail, and initially to FIGS. 1 to 3, there is shown a straight, cylindrical spinning tube 20 whose axial sections define portions of an elongated channel differing in cross-sectional shape and size. The tube 20 is axially aligned with the nip between a pair of delivery rollers 5 of a conventional drawing frame of which only two belts 5a are shown. A sliver 1 of staple fibers is discharged from the drawing frame and delivered by the rollers 5 to the bore or channel of the tube 20. A sliver 2 of continuous filaments enters the nip of the rollers S from a separate source, not shown, after being wrapped over one of the rollers 5 in laterally'spaced relationship to the staple fiber sliver 1. r j

The terminal section of the tube 20 near the rollers 5 is formed with a slot 6 constituting an intake or suction nozzle of thetube. The outer end ofthe-slot 6 is almost as wide as'the diameter of the tube 20. It tapers asymmetrically inward of the tube 20 so that its inner end extends from the tube axis toward a thin wall portion of the tube 20, as is best seen in FIG. 2. The thickness of the slot is uniform except for slightly flaring walls at its intake end, as is shown in FIG. 1. The generally elongated cross section of the slot is evident from joint consideration of FIGS. 1 and 2.

The inner end of the slot 6 communicateswith an ax} ially adjacent cylindrical chamber 8 which encloses a the helical duct in the chamber 8 with'an axial portion communicates with the twisting portion 9 through four of the channel and has, an axial component toward the third section. Means are provided for conveying fibers sequentially through the aforementioned three basic sections, whereby a twist is impartedto the fibers in the the fibers in the twisting portion from being propagated to the fibers in the slot of the first section.

9 of the tube borewhich is cylindrical, and whose diameter is greater than that of the passage 8a, but smallerthan that of the chamber 8, as is best seen in FIG. 3. The wall of the portion 9, hereinafter referred to as the twisting portion of the tube bore, is provided with an annular distributing duct 9b near the passage 8a which is connected to a compressed-air line 11 and nozzles 9a. The orifices of the nozzles are directed to discharge respective air jets having a tangential component relative to the-wall of the portion 9 and an axial component away from the passage 8a. The jets combine in an air stream 11a which forms a tubular shell of rapidly rotating air flowing axially toward the right, as viewed in the drawing, about a less rapidly moving air core. The jets function as injectors which draw a stream I2 of ambient air into the intake nozzle.6, through the helical duct in the chambers, and through the passage 8a into the twisting portion 9.

- The discharge end of the portion 9 is coa'xially joined by a chamber which has an axially central cylindrical portion of a diameter similar to that of the chamber 8 and an axial length of several timesits diameter, and terminal parts which taper conically in both axial directions toward the twisting portion 9 and toward the circular discharge orifice 13 of the tube 20. The nip of a pair of non-illustrated pull rolls, identical with or closely similarto the rollers 5, is aligned with the axis of the tube near the orifice 13. I

FIGS. 1,- 2, and 3 are drawn approximately to scale. Thediameter of the twisting section in the actual embodiment of the'invention illustrated in the drawing is 2 mm, and the flow sections of the narrow inner part of the nozzle 6 and of the helical guide duct in the chamber 8 are approximately equal to that of the twisting portion 9. The height of the slot 6 is'7 mm. at the inner end thereof. The diameter of the chamber 8 is 8 mm and about equal to its axial length. The shaft or stem portion of the screw 7 has a diameter similar to that of the twisting portion 9.. Air enters the. twisting portion 9 under a pressure sufficient'to discharge a spun yarn 4 from the orifice 13 at a rate which may be adjusted between 300 and 600 meters per minute bya non-illustrated valve in the compressed air line 1 l.

The tube 20 is assembled from several axial sections of abrasion resistant alumina in-an obvious manner, not illustrated, and the guide screw 7 consists of the same material and'is fixedly fastened in the chamber 8.

. The afore-described apparatus is operated as follows:

chamber 10 through the flaring intake end of the latter, the circumferential and axial velocity of the air stream is reduced sharply, and the yarnhelix expands into a balloon in which the slower air stream can no longer maintain the tension necessary for the tight twist characteristic of the yarn portion 4a. As the tension relaxes, the yarn 4a starts untwisting, whereby the helix of the shell of relatively loosely twisted staple fiber ends is -ultimately. reversed to a left-handed .or S-twist and the right-handed pitch of the core increases until an equilibrium is reached in which the resistanceto tighter left-handed twist in the shell balances the untwisting tendency of the core.

A stable yarn 4 having a core of right-handed twist and a shell of left-handed twist'is discharged from the orifice 13 by the released air and/or by the force of the non-illustrated pull rolls. While only the innermost core portion and the outermost part of the shell have been shown in FIG. 4 for the sake of clarity, it will be appreciated that the right-handed pitch gradually increases from the center of the yarn outward and firmly cohere.

The weight of the synthetic staple fibers in the silver As the slivers 1, 2 travel undertensio'n through the helical duct in the chamber 8, they are closely held to the stem portion of the guide screw 7 under substantial friction although all surfaces of the screw arepolished and smooth. The twisting motion imparted to the textile material by the air stream 11a in the twisting portion 9 is transmitted through the slivers 1,2 along a portionof the screw 7 toward the slot 6 so that the two slivers 1 are gradually twisted together as they travel through the chamber 8, the loose ends 3 of the staple fibers being drawn last into a sharply twisted yarn 4a which forms in the twisting chamber 9, the twist of-the yarn core reaching its highest value promptly upon entering the section 9. Propagation of this twist into-the slot 6 isprevented by the braking effectof the screw 7.

As somewhat diagrammatically illustrated in FIG. 4, theyarn 4a has acore tightlytwisted into-a righthanded or Z-spiral constituted by, the continuous filaments of the sliver 2 and a portion of the staple fibers of the sliver I firmly to interlock the two types of material, and a shell of originally loose staple'fiber ends 3, the tightness of the twist in the yarn 4a decreasing gradually in a direction radially outward from .the axis of the yarn 4a.

Even short cotton staple fibers have been spun successfully in this manner with 40 denier, continuous-filament fibers of synthetic material, such as Trevira,

' ple fibers and specific continuous filaments.

Strongest. yarns are generally obtained if the staple.

fibers employed are of an average length, at least equal to, but preferably greater than, the distance between the nip of the rollers 5 and the screw 7, and the distance between the latter and the discharge end of the twisting portion 9. The'longer the staplefibers and their loose ends, the greater the residual twist in the core of the yarn 4 ultimately produced. i v The apparatus shown is merely a preferred embodiment of the invention capable of many variations and modifications without exceeding the scope of the invention. The nozzles 9a simultaneously perform the functions of generating the helical air stream 1 lain the twisting portion 9, and-of thereby generating the air stream 12. Ultimately, the air stream 11a discharged by the nozzles 9a holds the formingiyarn 4a in frictional contact with, the stem portion of the screw 7. Obviously, these functions could be performed by individual devices.

Thus, air nozzles may be provided in the terminal section of the tube 20 in the manner of the nozzles 9a to draw the air stream 12 into the channel of the tube 20 or to reinforce the suction effect of thestream 11a.

When the air stream 11a and the yarn 4a; helically shaped under'the influence ofthe air, enter the' screw 7 could be achieved by conventional yarn guides if so desired.

should be understood, therefore, that the foregoing disclosure relates only to a preferred embodiment of the invention and that it is intended to cover all changes and modifications of the example of the invention chosen herein for the purpose of the disclosure which do not constitute departures from the spirit and scope of the invention set forth in the appended claims.

What is claimed is: l. A-method of spinning a yarn from a first elongated sliver of staple fibers and a second elongated sliver of continuous filaments which comprises:

a. passing said fibers and said filaments sequentially through an'intake zone, a braking zone, a twisting zone, and a relaxing zone;

b. moving said slivers in said intake zone longitudinally in transversely offset relationship;

c. laterally spreading loose ends of said staple fibers from the remainder of said first sliver during passage through said intake zone;

generating a helical air stream in said twisting zone about said slivers at a velocity sufficient to twist said slivers until a yarn having a tightly twisted core portion predominantly constituted by said filaments and said remainder and a less tightly twisted shellI portion predominantly con-stituted by said loose ends is formed I e. braking said slivers in said braking zone and thereby preventing propagation of said twisting into said intake zone; f. relaxing the twisting action of said air stream on said yarn in said relaxing zone until said core portion partly untwists, the twist in said shell portion is reversed, and the reversed twist in'said shell portion balances the remaining twist in, said core portion; and discharging from said relaxing zone the yarn having balancing'opposite twists in said core portion and in said shell portion thereof. 7

2. A method as set forth in claim 1, wherein said slivers are moved in said braking zone in frictional engagement with a helical wall, and are twisted while in contact with said wall as they approach said twisting zon'e.

3 Pneumatic spinning apparatus comprising:

a. a plurality of sequentially communicatingvtubular sections jointly defining an elongated channel,

i. said twisting portion being of circular cross section,

3. a third section defining therein a chamber portion of said channel having a cross section much greater than the cross section of said twisting portion; 3

' b. means for generating an air stream in said slot, said air stream having a first component longitudinal of said channel and a second component longitudinal of said cross section;

c. means for generating a helical air stream in said twisting portion having an axial component'toward said thirdsection; d. means for conveying fibers sequentially through the portions of said channel in said first, second, and third sections, whereby a twist is imparted to said fibers in said twisting portion by said helical air stream; and

e. brake means interposed between said first and second sections for preventing twist imparted to said fibers in said .twisting portion from being propagated tosaid fibers in said slot.

4. Apparatus as set forth in claim 3, wherein said brake means include a screw member having an axis, an axial stem portion, and a helical flight portion about said axis, and means for holding the conveyed fibers in frictional engagement with said stem portion.

5. Apparatus as set forth in claim 4, wherein said axis extends longitudinally of said channel.

6. Apparatus as set forth in claim 4, wherein said flight portion bounds a helical guide duct about said axis, an axial end of said duct directly communicating with said slot.

7. Apparatus as set forth in claim 6, wherein an additional one of said sections connects said brake means and said second section, said additional section defining a passage portion of said channel directly communicating with said guide duct and said twisting portion, the cross section of said passage-portion being substa'ntially smaller than the cross section of said twisting portion.

8. Apparatus as set forth in .claim 3, wherein said means for generating a helical air stream includes nozzle' means for directing an air jet under pressure into said twisting zone in a direction obliquely inclined relative to the direction of elongation of said channel and substantially tangential to the cross section of said twisting portion. Q 9. Apparatus as set forth in claim 3, wherein said chamber portion has two terminal parts tapering outward of said-chamber portion. I I 10. Apparatus as set forth in claim 3, wherein said slot tapers inwardly of, said channel in the direction of elongation of said cross section thereof.

i i i 

1. A method of spinning a yarn from a first elongated sliver of staple fibers and a second elongated sliver of continuous filaments which comprises: a. passing said fibers and said filaments sequentially through an intake zone, a braking zone, a twisting zone, and a relaxing zone; b. moving said slivers in said intake zone longitudinally in transversely offset relationship; c. laterally spreading loose ends of said staple fibers from the remainder of said first sliver during passage through said intake zone; d. generating a helical air stream in said twisting zone about said slivers at a velocity sufficient to twist said slivers until a yarn having a tightly twisted core portion predominantly constituted by said filaments and said remainder and a less tightly twisted shell portion predominantly constituted by said loose ends is formed; e. braking said slivers in said braking zone and thereby preventing propagation of said twisting into said intake zone; f. relaxing the twisting action of said air stream on said yarn in said relaxing zone until said core portion partly untwists, the twist in said shell portion is reversed, and the reversed twist in said shell portion balances the remaining twist in said core portion; and g. discharging from said relaxing zone the yarn having balancing opposite twists in said core portion and in said shell portion thereof.
 2. A method as set forth in claim 1, wherein said slivers are moved in said braking zone in frictional engagement with a helical wall, and are twisted while in contact with said wall as they approach said twisting zone.
 2. a second section defining a twisting portion of said channel, i. said twisting portion being of circular cross section,
 3. Pneumatic spinning apparatus comprising: a. a plurality of sequentially communicating tubular sections jointly defining an elongated channel,
 3. a third section defining therein a chamber portion of said channel having a cross section much greater than the cross section of said twisting portion; b. means for generating an air stream in said slot, said air stream having a first component longitudinal of said channel and a second component longitudinal of said cross section; c. means for generating a helical air stream in said twisting portion having an axial component toward said third section; d. means for conveying fibers sequentially through the portions of said channel in said first, second, and third sections, whereby a twist is imparted to said fibers in said twisting portion by said helical air stream; and e. brake means interposed between said first and second sections for preventing twist imparted to said fibers in said twisting portion from being propagated to said fibers in said slot.
 4. Apparatus as set forth in claim 3, wherein said brake means include a screw member having an axis, an axial stem portion, and a helical flight portion about said axis, and means for holding the conveyed fibers in frictional engagement with said stem portion.
 5. Apparatus as set forth in claim 4, wherein said axis extends longitudinally of said channel.
 6. Apparatus as set forth in claim 4, wherein said flight portion bounds a helical guide duct about said axis, an axial end of said duct directly communicating with said slot.
 7. Apparatus as set forth in claim 6, wherein an additional one of said sections connects said brake means and said second section, said additional section defining a passage portion of said channel directly communicating with said guide duct and said twisting portion, the cross section of said passage portion being substantially smaller than the cross section of said twisting portion.
 8. Apparatus as set forth in claim 3, wherein said means for generating a helical air stream includes nozzle means for directing an air jet under pressure into said twisting zone in a direction obliquely inclined relative To the direction of elongation of said channel and substantially tangential to the cross section of said twisting portion.
 9. Apparatus as set forth in claim 3, wherein said chamber portion has two terminal parts tapering outward of said chamber portion.
 10. Apparatus as set forth in claim 3, wherein said slot tapers inwardly of said channel in the direction of elongation of said cross section thereof. 